PHILADELPHIA (Reuters) - A city medical examiner described fetal body parts stored in pet food containers during his testimony on Monday at a murder trial that has drawn a national spotlight after anti-abortion groups complained that it was being ignored.

The graphic testimony came in the fifth week of the murder trial of Dr. Kermit Gosnell, 72, who faces the death penalty if convicted of charges he killed seven infants and a female patient at what a grand jury described as his squalid abortion clinic in urban West Philadelphia.

"It was the first time I had to deal with fetuses that were frozen and that I had to thaw out," Philadelphia Chief Medical Examiner Sam Gulino testified about the contents of pet food containers received from the Women's Medical Society Clinic in 2009 and 2010.

The horror story unfolding in daily testimony since the trial began in Common Pleas Court in March has been largely ignored by national media, and anti-abortion advocates have criticized the silence, claiming a media bias toward abortion rights and touching off a political firestorm.

The criticism went viral online and was echoed by Congressional Republicans. Washington Post blogger Melinda Henneberger scoffed at some media arguments that the trial was largely ignored because it was too lurid or because it involved low-income residents, saying "the only abortion story most outlets ever cover in the news pages is every single threat or perceived threat to abortion rights."

Reuters covered opening arguments of the Gosnell trial in March but has not maintained a daily presence during the trial.

The charges against Gosnell have rekindled the debate in the United States about late-term abortions. Under Pennsylvania law, abortions can be performed for up to 24 weeks.

In the wake of criticism about the news coverage, national media outlets packed the courthouse on Monday, prompting Judge Jeffrey Minehart to warn the jury not to read articles about the trial, noting, "It has come to my attention that the media in this case has increased."

Gosnell is accused of severing infants' spinal chords after they lived through an abortion procedure.

Medical examiner Gulino told the jury that he found three of fetuses he checked may have been viable, that is able to live outside of the mother's body on their own.

He said he estimated gestational age of the fetuses, in many cases using foot measurements.

Some containers he received held only feet, and in one case only part of a pelvis and a right leg. He determined that fetus was 14 to 15 weeks old.

Gosnell's defense lawyer, John McMahon, has characterized the prosecution of his client, who is black, as "elitist, racist" and said, "They (prosecutors) want to put a Mayo Clinic standard on a West Philadelphia clinic."

Gosnell has been in jail since he was charged in January 2011 after a grand jury probe. He is on trial on 26 charges, including 8 counts of murder for the deaths of seven infants and a female patient. If convicted of murder in the woman's death, which prosecutors have said was caused by an overdose of drugs administered by the clinic, Gosnell faces the death penalty.

Nine others in the clinic were charged with crimes and all but one of them has pleaded guilty.

"The medical practice by which he carried out this business was a fraud in which he overdosed his patients with dangerous drugs, spread venereal disease among them with infected instruments, perforated their wombs and bowels, and on at least two occasions caused their deaths," the grand jury report said.